Geographical environment of Irrawaddy River

The longest river in Myanmar runs through the central part of Myanmar, all within the territory of Myanmar, with a total length of about 2 170 km (1 350 miles). From Jiangyuan to many estuaries, rivers flow completely in Myanmar. The total drainage area is about 4 1 1 000 square kilometers (158,700 square miles). The average annual runoff of Irrawaddy River is about 486 billion cubic meters. This valley has become the historical, cultural and economic center of Myanmar. Irrawaddy River is the main artery of inland transportation in Myanmar, and it is navigable from 1 730 km below Myitkyina. Valley plain is the most important agricultural area in Myanmar, with oil fields in the middle reaches and rice in the downstream delta. Major cities along the main stream are densely populated.

As one of the great rivers in Indochina Peninsula of Asia, the total length of the river is 27 14 km, and the drainage area is 430,000 square kilometers. The whole basin is sandwiched between Xishan Mountain and Shan Plateau, showing a north-south belt shape, and the estuary section is a fan delta (30,000 square kilometers). The geographical location of the basin is north latitude 15. 30'~28。 93 degrees 50 minutes east longitude. 16'-98。 42'。

Irrawaddy River is the largest river in Myanmar, with two tributaries at its source. The east source is the Nmai Hka River, which originated near Chayu, China, and the west source is the MaliHka River, which originated in the mountainous area of northern Myanmar. These two rivers were called Irrawaddy River only after they joined at Guidao, about 50 kilometers north of Myitkyina. The total length of the river is 27 14km, and the drainage area is 410000km2, accounting for about 60% of Myanmar's national area. A central longitudinal valley is formed along the Irrawaddy River, and the valley area accounts for 1/3 of the national area. Irrawaddy River is the lower reaches below Deyemiu.

Enmeikai River (Ji Tai Qu) is a river in the Indian Ocean system and the upstream source of Irrawaddy River. Located in Chayu County. Originating at 20km northeast of Chayu County, it flows to the southeast, flows into Yunnan Province about 6km northwest of Debrie, turns to Myanmar in the west, turns to Milikai River in the south, then turns to Irrawaddy River, and finally flows into the Indian Ocean. Tibet is 77 kilometers long and 30 kilometers wide on average. The basin is rectangular with an area of 265,438+050 square kilometers. Ji Tai Qu flows through the high mountains and canyons, with rapid water flow, with an average annual flow of 52.8 cubic meters per second and an average annual runoff of 65.438+67 billion cubic meters. The tributary is short, and the main tributary Mudong Canal is 64 kilometers long. Irrawaddy River is formed by the confluence of Enmeikai River and Melikai River. Both tributaries originate from remote alpine glaciers near 28 north latitude in northern Myanmar. Enmeikai River, a tributary to the east, originates from Langra Glacier, which has a large amount of water, but it is actually navigable due to the rapid flow of water. The slope of Mailikai River, a tributary to the west, is relatively gentle, and some sections are navigable, but it is interrupted by rapids and rapids. About 48 kilometers (30 miles) south of the confluence is Myitkyina. The topography of the basin is high in the north and low in the south. Topographic features are high mountains and valleys in the north, high mountains and mountains in the west, plateau in the east and low-lying plains in the south. The Irrawaddy River basin is located between the western mountainous area and the Shan Plateau. There are remnants of volcanic lava topography in the valley, and some areas are alluvial plains of Irrawaddy River, Qindun River and Xitang River, which can be divided into five communities: upstream valley, middle valley, downstream valley and delta, Bo Gu Mountain and Xitang River valley. The upper valley is mountainous, there are prominent hills on the middle valley plain, and the lower valley plain is narrow and gradually widens near the delta.

On both sides are cliffs 6 1~9 1 m (200~300 feet) high. The river flows into the third gorge of Mogaoke, about 97 kilometers (60 miles) north of Mandalay. Between Kata and Mandalay, the river is very straight and almost flows due south, but near Kabwe, a volcanic rock causes the river to suddenly bend westward. After Kyaukphyu flows out of the third canyon, the river flows through the central arid zone, the center of ancient culture, along a wide and open river, where there is a large area composed of alluvial plains. The river suddenly bends westward from Mandalay (the capital of the former kingdom of Myanmar), then turns southwest to join the Khindwin River, and then continues to flow southwest. After joining the Chindun River, the Irrawaddy River continued to meander and run, passing through densely populated arid areas, reaching yenangyaung, and then most of it flowed south. It flows through a narrow valley between Mingbu and Prom in the lower reaches, with forest-covered mountains on both sides-the peak of Arakan Mountain in the west and the peak of Pei Gu Shan in the east.

Between Myitkyina and Mandalay, the Irrawaddy River flows through three obvious canyons. About 65 kilometers (40 miles) downstream of Myitkyina is the first canyon. The river suddenly bends westward under the Ba Maw, leaving the alluvial basin in Ba Maw and cutting limestone to form a second canyon. The narrowest part of the second canyon is about 9 1 m (300 feet) wide, and there are cliffs 6 1~9 1 m (200~300 feet) high on both sides. The river flows into the third gorge of Mogaoke, about 97 kilometers (60 miles) north of Mandalay. Between Caesar and Mandalay.

The Irrawaddy River Delta can be said to start from 93 kilometers (58 miles) above Henzada. The apex of the delta is about 290 kilometers (180 miles) from the bottom of the arc facing the Andaman Sea. The two sides of the delta consist of Bo Gu Mountain in the east and the southern end of Arakan Mountain in the west. The westernmost tributary of the delta is the Bassein River, and the easternmost river is the yangon river, and Yangon, the capital of Myanmar, is built on its left bank.

1 year, the discharge of Irrawaddy River and its tributaries fluctuates greatly, mainly due to the monsoon rainfall from June to September, and the rapid melting of glaciers in summer further increases the discharge. The average flow at the top of the delta is between 2300 and 32600 cubic meters per second (82000 to 1. 152000 cubic feet per second); The annual average flow is13000m3/s (460,000m3/s). The lowest water level appears in February and the highest water level appears in August. The measured maximum discharge of Irrawaddy River is 64,000m3/s, and the minimum discharge is1.306m3/s; The measured average sediment concentration at each control station is 0.62ks/m3, with an average annual sediment discharge of 300 million t. The average annual runoff of Irrawaddy River is 486 billion cubic meters, including 455 billion cubic meters in Myanmar, accounting for about 40% of the total river runoff in Myanmar. The Irrawaddy River is also rich in hydropower resources, especially in the northern alpine valleys, where the water level difference is large; Its main tributary, Qindun River, is rich in hydropower resources.